Smoking is the number one preventable cause of cancer, and is not equivalent to other potential carcinogens like processed meat.

Pexels: Irina Iriser

So you can end up with two different carcinogens in the same IARC grouping, where one will hugely increase your risk of getting cancer and the other might just shift it by a minuscule percentage, Dr Saunders said.

For example, processed meat — including salami, sausages and bacon — is in Group 1, along with tobacco smoke, plutonium, asbestos and even sunlight (solar radiation).

Experts said that you can still consume processed meat in moderation, so don't worry about a bacon ban.

Unsplash: Pam Menegakis

Unlike occasionally eating sausages or ham, there is no safe level of smoking — and this is critical for the way that risk is communicated, according to Anita Dessaix, director of cancer prevention and advocacy at Cancer Council New South Wales.

"The relative risk of consuming too much processed meat is a lot smaller compared to something like tobacco," Ms Dessaix said.

So the Cancer Council focuses its efforts on what will make the most difference to the community.

"We assess the evidence, look at the relative risk of different products or carcinogens, and ensure that we're communicating to the public in a way that can make the biggest gains to improve their lifestyle and, in effect, reduce their cancer risk," she said.

How to make sense of contradictory health news

"When agencies like IARC release this type of content, we have to make sure we're framing it in a way that's not just raising fear for fear's sake, but actually providing practical information."

Dr Saunders said when the IARC findings about meat came out, he spoke to a chef concerned about the effect on his business.

"I was discussing this problem with a chef and he said, 'All my customers aren't going to want to eat steak anymore'," Dr Saunders said.

"I told him that if you put it into context, driving a car to the restaurant, drinking a couple of glasses of red wine, and then smoking a cigarette on the way home are all far more likely to increase your risk of cancer than having a steak.

"He looked at me and said, 'I hadn't thought of it like that before'."

Weed-killer back in the news

When people see cancer in the media, scientific evidence does not really factor into their response, according to science communication expert Rod Lamberts from the Australian National University.

"The reality of the human calculation is that risk equals 'what the f**k' times 'oh my god'," Dr Lamberts said.

"Which is basically how horrifying does it sound, and how bad would it be if it happened to you.

"So it's not about the reality of it scientifically — it's just about whether it sounds horrific or not."

Glyphosate, sold as Roundup, is one of Australia's most common weedkillers.

Glyphosate, sold as Roundup, is one of Australia's most common weedkillers.

Rose Grant: ABC Rural

A common garden chemical that could give us cancer is bound to get our hackles up, Dr Lamberts said.

"Cancer is horrifying, and the idea you get it from your gardening would outrage you, therefore people are freaked out," he said.

The 2015 IARC report on glyphosate concluded that "glyphosate is probably carcinogenic to humans" and placed it in the category Group 2A — along with consuming red meat, drinking very hot beverages, and shift work that disrupts your circadian rhythm.

Glyphosate resurfaced in the news this year when a jury in a US court case declared the weed-killing product Roundup was a factor in causing a man's terminal cancer, and that the company Monsanto (now Bayer) failed to warn of its risks.

Despite the IARC using considered language, stating that there was "limited evidence in humans for the carcinogenicity of glyphosate" and that "a positive association has been observed for non-Hodgkin lymphoma", the looming shadow of a chemical giant can influence how people think about glyphosate and cancer.

Dr Lamberts said when it came to dealing with big corporations like Monsanto, "hardcore tribalism" often kicked in.

"Monsanto is cast as the nasty company that doesn't give a toss about anyone else. Which means that any negative stuff [about glyphosate and cancer] is going to be believed and amplified," he said.

Beware sensational cancer headlines

Despite researchers' best efforts, the news media's need for attention-grabbing headlines often trumps careful consideration of the evidence.

"We did see a few media outlets — particularly in the English-language coverage — that played on fears and confused the public, without asking their source any questions.

"This was compounded by the huge vested interests that felt that these results were an obstacle to their activities, and had a clear interest in denigrating the process, the results and their communication."

What to look out for wghen cancer is in the news

Tips for interpreting news about cancer

It's important to read the whole story, not just the headline

Keep an eye out for caveats. Research on carcinogens — including processed meat, red meat, and glyphosate — can come with caveats, and people often miss the part of the story that explains why a substance might not be harmful

Keep an eye out for whether the research is about the evidence that something causes cancer (like the IARC reports), or the actual risk of a substance causing cancer

Remember, strong evidence that an agent can cause cancer doesn't mean there's a high likelihood that it will give you cancer

Misleading health headlines are nothing new.

But when it comes to stories about cancer, the consequences of poor reporting can be real, and serious.

Dr Saunders said misreporting of cancer science — including IARC findings — can confuse cancer patients about their disease and recovery.

Once people have a cancer diagnosis, the stakes are high.

"A lot of people misunderstand that just because something might be a risk factor for giving you cancer, like smoking, doesn't mean that if you take away that thing away … it will act as a therapy or cure," he said.

"There are particular things in the diet that make us more susceptible to getting cancer, but taking those things out of your diet once you've got cancer isn't necessarily going to make the cancer go away."

Another risk of unclear media coverage of cancer is that it can play into a public perception that nearly everything causes cancer, Ms Dessaix said.

"There's this situation where you can feel the community throw their arms up in the air and say, 'There's nothing that we can do, everything causes cancer, we give up'."

And that is why they are careful to communicate with the public effectively about their cancer risk, she said.

Ms Dessaix encouraged people to contact agencies like the Cancer Council or their doctor if they were worried about something they had seen in the news about cancer.

"If they do want further information about cancer risk factors, or if they're going through a cancer experience, anyone can reach out to to our support line (13 11 20)," she said.

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